REPRODUCTION AND DEVELOPMENT 115 



While in this position the young leeches develop until anterior 

 and posterior suckers are well formed and there is a nervous system 

 capable of co-ordinating their activity. They then hatch from the 

 egg, lose their attachment by the larval organ and hold on to the 

 parent by their posterior suckers. In this position they may be 

 carried about by the parent for several weeks or months, according 



Fig. 67. Young Glossiphonia complanata taking their first meal 

 of blood from an Erpobdella:- From Pawlowski, 1955. 



to the species. Glossiphonia complanata holds the eggs in the 

 cocoon for 5-6 days, holds them by the embryonic attachment 

 organ for 4-5 days and then shelters the young leeches which are 

 holding by their posterior suckers for up to 14 days so that the 

 whole process occupies about 24 days (Mann, 1957a). Theromyzon 

 tessulatum on the other hand may hold the eggs in the capsules for 



